Shrub growth keeps a vicious feedback from enhancing climate change.

Although the climate changes that are being driven by human carbon emissions are likely to cause serious disruptions on their own, one of the additional worries is that the initial warming will set off events that keep changing the planet even if humanity gets its carbon emissions under control. So, for example, warming the oceans could heat up the clathrates that exist there, releasing methane that greatly enhances the greenhouse warming.

The other place that scientists have been watching nervously is the Arctic. About half the carbon stored in the Earth's soil is in the Arctic, where it's locked in place by permafrost and low metabolic activity caused by the cold. As those regions melt, the worry is that bacteria in the soil will start feeding on the carbon trapped there, releasing it into the atmosphere as CO2 that causes further warming.

A new study that looks at 20 years of changes in Alaska, however, suggests that this won't necessarily take place. In the area being studied, the warming temperatures rearranged the ecosystem and redistributed the carbon. But, in the end, there was just as much carbon stored in the soil. What needs to be determined now is just how well this experience will translate to other areas of the Arctic.

To study the impact of the greenhouse effect, scientists set up an actual greenhouse above some tundra in Alaska. Although that works through a completely different mechanism, it has the same sort of effect, warming the soil below it. The greenhouse was put in place back in 1989, and the researchers have spent the decades since tracking the changes that happen in the soil beneath it.

As had been seen at other sites, the warming promoted the growth of woody shrubs—cover rose by a hefty 94 percent. These lead to further warming of the soil by trapping snow in the winter; the snow then acts as an insulator, keeping things warmer than they would be otherwise. However, the researchers found that there was also a short-term summer time warming that persisted for several years as the shrubs were growing.

The plants ended up proliferating at the expense of mosses and lichens, both of which decline precipitously (lichens effectively vanished, with their presence dropping by 99 percent). That shifted the dynamics of the microbial ecosystem in the surface soils. Dead needles from the shrubs break down far more readily than mosses, which increased the speed at which carbon was turned over in the soil. That added warmth also increased the activity of bacteria in the soil, accelerating the decomposition further. The net result was that less carbon ended up stored in the surface soils.

All of that would suggest that initial worries were well founded. But something else happened as a result of the shift to shrubs: root systems began to penetrate far deeper into the soil, and reached depths below the areas that were typically rich in organic matter. And, as the roots penetrated, an ecosystem followed, living off dead roots and organic material that leached from living ones. These microbes eventually attracted more creatures that fed on them, eventually resulting in a significant carbon-based system well below the surface layers.

All told, this deep carbon, combined with the increased storage in the form of shrubs, offset the loss from the surface. The change, in effect, was carbon neutral.

The big remaining question is whether this sort of effect is general. Different shrubs may take over in other regions of the Arctic, and there are some areas that may be perpetually inhospitable to these plants. Nevertheless, if this sort of behavior holds up, then we might be able to breathe a bit easier about the future fate of the Arctic's carbon.

Huh. No flames? The author steps in early and slaps his ruler on the table, and everybody straightens up. Love it. And as to your first thing John ( I hope I can call you John by now ), the voting simply sucks; it has no place here, like it would, say, on a site about Beiber's latest wardrobe. People that want to vote people down, should have to vote them down with words and ideas, not a click and run.

If i can call you "tower", sure...

Anyway, voting serves a valuable purpose. Lots of stupid, off-topic distractions get posted; voting lets people know that in a very minimal effort manner. Plus the post gets collapsed and is no longer a distraction.

Yeah, i looked over the abstract of that paper on Saturday. The IPCC report is now long past being closed to new research; this won't make the cut.

Anyway, as far as this particular paper goes, it's not any sort of "pushback" - basically, it's taking recent trends and trying to see what they say about different climate models. As it notes, rather than warming the atmosphere, the greenhouse forcings are warming the oceans lately. There's also an extremely prolonged La Niña happening, which has moderated things (and may or may not be related to the changes in ocean heat content).

There are two reasons i'm hesitant to give this (and a few other studies like it that have come out recently) too much weight:1) we're still within a couple of standard deviations of the existing climate models, so it's not even clear if there's anything that needs refining yet.2) Until we see what the climate does when we're out of the La Niña, i'm hesitant to conclude that the recent flattening out is anything other than that.

If one of the freelancers wants to cover this, i'm fine with it. But until i clarify my thoughts on 1 and 2, and talk to some people in the field, i don't think i want to.

Anyway, the stored ocean heat thing isn't so much ominous as inevitable. The planet will necessarily be forced to a warmer state by the greenhouse gasses. But we won't reach that state immediately - they warm the atmosphere, but that heat needs to be equilibrated with the ocean before the planet stabilizes in a new state. So, we knew this would happen, just not how quickly.

You're the star and I'm just the fan here (in this little universe), so I'll be thrilled when you call me at all. Also, you could use Geoff.

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Anyway, voting serves a valuable purpose. Lots of stupid, off-topic distractions get posted; voting lets people know that in a very minimal effort manner. Plus the post gets collapsed and is no longer a distraction.

Not lots. Anywhere from 0 to a dozen posts on longer threads qualify as really off topic. Stupid posts are more numerous, but I don't want that judged by committee before I even get home from work. And sometimes, there's a real gem collapsed, an unpopular viewpoint maybe; you have to expand each and every one to know. But before they collapse, they turn such a light shade of grey, one has to use the text selection tool to highlight and read it.

And most discussions here are 3 ish pages; there's just not the volume to need any filtering. It doesn't "add" anything to the discussion. If you had Slashdot volume, then you'd have to do something. Right now it solves a problem you never had, and ruins the whole plebeian forum thing, as if unpopular voices are being shouted down before they can be heard.

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... still within a couple of standard deviations of the existing climate models ... La Niña ...

I see. If you wanted to do a filler type of thing while you collate, you could do "Why the urban heat island effect isn't the big deal towermac thinks it is." It's just a thought.

...All of them show there's no urbanization effect. The horse is truly dead, and you can stop beating it.

Not really, no they dont:

"The Urban Heat Island (UHI) effect describes the observation that temperatures in a city are often higher than in its rural surroundings. London was the first urban heat island to be documented... .. The UHI effect can be attributed to many physical differences between urban and rural areas, including absorption of sunlight, increased heat storage of manmade surfaces, obstruction of re-radiation by buildings, absence of plant transpiration, differences in air circulation, and other phenomena (Oke, 1982)."

So there is an urbanization effect. That paper goes on to show there's still global warming even without considering the possibly skewed urban measurements. Not the same thing as no effect.

But it's your forum man. I don't mean beat anything you don't want to talk about, whether dead or just ailing. It's an area that greatly interests me, which is why I mentioned it. Thank you for the links.

...All of them show there's no urbanization effect. The horse is truly dead, and you can stop beating it.

Not really, no they dont.

Ok, poorly phrased (and this is from someone who lives in NYC, and suffers from it every summer). Urbanization has a negligible impact on the global temperature record. Using your words, it's not a big deal.

Anyway, as far as this particular paper goes, it's not any sort of "pushback" - basically, it's taking recent trends and trying to see what they say about different climate models. As it notes, rather than warming the atmosphere, the greenhouse forcings are warming the oceans lately. There's also an extremely prolonged La Niña happening, which has moderated things (and may or may not be related to the changes in ocean heat content).

There are two reasons i'm hesitant to give this (and a few other studies like it that have come out recently) too much weight:1) we're still within a couple of standard deviations of the existing climate models, so it's not even clear if there's anything that needs refining yet.2) Until we see what the climate does when we're out of the La Niña, i'm hesitant to conclude that the recent flattening out is anything other than that.

Could you point out the "extremely prolonged" La Niña below? I'm not seeing it. On the other hand,looking at this chart, there was quite a tilt towards El Niño during the 90's. Funny how no one ever said "Until we see what the climate does when we're out of the El Niño, I'm hesitant to believe the AGW models".

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If one of the freelancers wants to cover this, i'm fine with it. But until i clarify my thoughts on 1 and 2, and talk to some people in the field, i don't think i want to.

Anyway, the stored ocean heat thing isn't so much ominous as inevitable. The planet will necessarily be forced to a warmer state by the greenhouse gasses. But we won't reach that state immediately - they warm the atmosphere, but that heat needs to be equilibrated with the ocean before the planet stabilizes in a new state. So, we knew this would happen, just not how quickly.

The "stored ocean heat thing" is a hypothesis at this point, not a measurement. Thermal expansion is touted as the main reason for accelerating sea level rise, and we're not yet seeing any.

Could you point out the "extremely prolonged" La Niña below? I'm not seeing it. On the other hand,looking at this chart, there was quite a tilt towards El Niño during the 90's.

We've not had a strong El Niño since 1998, and really none that's lasted a calendar year since 2005. At the same time we've had at least one strong La Niña - and, incidentally, have experienced the warmest La Niña year on record. Extremely prolonged was poor phrasing on my part (mea culpa). Strong tendency would have been better.

And, about the accelerating sea level rise, might be worth checking with Wikipedia, which says: "a range of evidence clearly shows that the rate of sea level rise increased between the mid-19th and mid-20th centuries."

Could you point out the "extremely prolonged" La Niña below? I'm not seeing it. On the other hand,looking at this chart, there was quite a tilt towards El Niño during the 90's.

We've not had a strong El Niño since 1998, and really none that's lasted a calendar year since 2005. At the same time we've had at least one strong La Niña - and, incidentally, have experienced the warmest La Niña year on record. Extremely prolonged was poor phrasing on my part (mea culpa). Strong tendency would have been better.

I'm aware of the article, just as I'm aware that it did not provide rigorous evidence of rising deep ocean temperatures. Essentially the claim is that the entire ocean has risen 0.04 deg C on average. In no way have worldwide, full ocean column measurements so far been precise enough to support that claim.

I recently posted this chart of sea surface temperatures:

It doesn't at all pass the sniff test that surface temperatures, which should be most affected by GHG warming, would go down as deep ocean temperatures rise. CO2 based warming dominates everything, according to the warmist alarmists.

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And, about the accelerating sea level rise, might be worth checking with Wikipedia, which says: "a range of evidence clearly shows that the rate of sea level rise increased between the mid-19th and mid-20th centuries."

So your claim is that sea level rise accelerated during a period of relatively low atmospheric CO2 concentrations, and is now stalled as CO2 has risen to the highest level in quite a while? Interesting take...

I'm aware of the article, just as I'm aware that it did not provide rigorous evidence of rising deep ocean temperatures. Essentially the claim is that the entire ocean has risen 0.04 deg C on average. In no way have worldwide, full ocean column measurements so far been precise enough to support that claim.